Booklets of the aforedescribed kind are normally produced in the following way.
A flat sheet of board and/or plastic material is folded to provide a cover that is divided into two cover sheets and a spine. A string of hot melt glue is applied to the inner surface of the spine. The cover sides are then folded in towards one another to form a cover with the glue string located between the sheets. The finished covers are then packed and delivered to the user, who takes a cover from the package and inserts a bundle of sheets between the cover sheets so that one side edge of the bundle is in abutment with the glue string. The user then places the cover and enclosed sheets in a binding apparatus, e.g. of the kind described in SE-B-434 367, in which the outer surface of the spine is brought into contact with a hot plate. The glue melts within a given space of time and the bundle of sheets sinks down into the molten glue. The user then removes the cover and sheet bundle from the binding apparatus and allows the glue to cool, so as to firmly affix the edges of the sheets in said bundle to the spine.
The aforedescribed method is both complicated and time-consuming, particularly when a large number of booklets of one and the same kind or of different kinds shall be produced.
U.S. Pat. No. 5,102,277 teaches a method and a machine for binding bundles or sets of sheets in covers of the aforedescribed kind. Although the method and the machine described are developments of the manual binding of sheets achieved with binding apparatuses according to SE-B-434 367, the method and machine do not enable bundles of sheets, e.g. dispensed from a copier, to be combined with the bundle of empty covers inserted into the machine.
U.S. Pat. No. 2,549,890 teaches a book-fabricating machine. Book blocks are provided with glue on their respective side surfaces and introduced into covers that fall down singly from a magazine in the machine. The machine thus produces products of a kind other than booklets, wherein each product consists of a cover that is affixed to a sheet bundle solely at the spine of the cover. Moreover, the machine does not include means for activating a glue string so as to affix the bundle of sheets to the spine of the cover.
GB-A-1,258,746 teaches a book-binding machine for producing book blocks by applying a melt glue along one edge of the book block. The machine thus produces products of a kind other than booklets which comprise bundles of sheets affixed to the spines of the booklets. Moreover, this machine does not include sheet-bundle and booklet transporting means.
U.S. Pat. No. 3,093,396 teaches a book-binding machine in which paper sheets are joined together along one side edge thereof by means of several adhesive layers, such as to form a book block. Each book block is then combined with a cover that lacks a binding agent, whereafter to adhesive layers on the book block are activated via the cover spine, to join the block to the spine. The machine thus produces products of a kind other than booklets that consist of covers having spine-applied glue strings that are interconnected with bundles of sheets that are loose relative to one another prior to binding. Moreover, the covers are not collected in any form of cassette or the like from which they are transported to book blocks in the known machine.
Finally, WO94/26535 teaches a method and a device corresponding to the method and device defined in the preambles of respective Claims 1 and 13. This method and device enable the manual work to be reduced, the production rate to be increased and the quality of the finished booklets to be improved in comparison with earlier known techniques.
The method and the device are, however, relatively complicated. This is due primarily to the provision of a separate station for the actual combining step. This step requires transport means for moving the sheet bundle and for moving a cover to the combining station. Furthermore, it is necessary that the sheet bundle and the cover are moved to the position in which they are to be combined with satisfactory precision, both with respect to time and position.